Summary of Theory (Note: Hagelstein has no "theory." Instead, he has an assortment of models that attempt to describe various aspects of the LENR phenomena.)

In a paper Peter Hagelstein wrote, he said that his model is based on "excitation transfer in which global energy is conserved but local energy conservation is violated." In the model, he said, "Two deuterons interact to make 4He, exchanging one or more phonons in the process, with the reaction energy transferred elsewhere. The coupling in this case is weak since the transition is hindered by the presence of a Gamow factor due to coupling through the Coulomb barrier."

Letter to Bockris, Dec. 15, 1993
There are numerous anomalies that have been reportedly observed in this field that many refer to as "cold fusion." As you are aware, I do not believe that fusion (especially d+d fusion) can occur in electrochemical cells. The idea that a lattice could somehow squeeze deuterons together sufficiently hard to get them to fuse seemed to me to be absurd when I first heard about it ... It is immediately clear that fusion is not the source of the anomalies.

ICCF-3 Trip Report (LENR theory review begins page 25) (1992)
The experimentalists have grown used to the idea that deuterium gives anomalies and hydrogen does not; the theorists who believe in fusion mechanisms are comfortable with positive effects in deuterium and negative effects in hydrogen. A light water heat effect causes consternation in both camps; it would be exceedingly difficult to reconcile with a fusion mechanism.

The neutron transfer model which I have been looking at (described briefly below) needs a neutron donor (usually deuterium) and an acceptor nucleus, and therefore has somewhat fewer constraints; nevertheless, I do not relish the prospect of attempting to explain an apparently general light water heat effect where the nuclei present are widely different from one cell to another. An experimental determination (and confirmation) of the ashes.

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It has been suggested that the 4He branch of the dd-fusion reaction is somehow favored, and several searches for 4He have been made. The conventional 4He branch yields a 24 MeV gamma, which is not observed when heat is produced. The reaction energy would have to go elsewhere to be qualitatively consistent, and many [people] in the field believe that energy transfer to the lattice occurs. Many measurements have been performed seeking 4He in the cathode after the experiment; my impression is that it is simply not there quantitatively by many orders of magnitude.I would think that by next year's conference, that there will be a consensus by many groups established on whether substantial helium is produced or not.

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A weakness of the limiting argument as stated by Morrison is the presupposition that conventional dd-fusion is the operative reaction mechanism; it has long been recognized by many (but not all) in the field that the excess heat production can not be due to conventional dd-fusion.

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The theories may initially be divided up into two general categories; those involving (modified) fusion mechanisms, and those not involving fusion mechanisms. Papers considering fusion mechanisms face the two basic problems of (1) arranging to get nuclei close enough together to fuse, and (2) possibly modifying the fusion reaction profiles. We first consider papers describing theories based on fusion mechanisms.

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A number of theorists, including myself, have gone away from fusion reaction mechanisms. The motivation for this is to avoid the coulomb barrier (if possible) and to find reactions with signatures that hopefully more closely match the experimental observations. Each new non-fusion approach carries with it specific problems and issues that are associated with the specific reaction mechanism. Aside from this, any new approach must also arrange itself to be consistent with physical law, observations in this and other fields, and must presumably be functioning in a manner not previously expected (lest it would have been found earlier). We describe such contributions below.

1. Electron capture on a deuteron would lead to two virtual neutrons; if it could be arranged for the virtual neutrons to be in proximity with neighboring nuclei, then further reactions could occur. This approach was described in two abstracts by J. Yang of the Dept. of Physics, Hunan Normal University of China.84,85 Yang proposes that the two neutrons form a stable dineutron that reacts with deuterium to make tritium and a free neutron, and with 105Pd to make 106Pd and a free neutron.

I consider this general approach to be one of the basic non-fusion approaches that actually begins to try to address the coulomb barrier problem. Once the electron capture occurs, the coulomb barrier is gone, potentially leading to the possibility of something happening near room temperature. One difficulty involved in this approach are that the electron capture is mediated by the weak interaction, which really is very weak, making it hard to obtain significant reaction rates. A second difficulty is that virtual neutrons do not generally wander more than fermis away from their point of origin, making it difficult for a virtual neutron to reach another nucleus to interact.

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The name “cold fusion” has been adopted by the field to some degree by default. This name implies a generic physical reaction mechanism (fusion), and because the experiments involve deuterium, the name further presupposes specific reactions (dd-fusion reactions). But dd-fusion is expected to produce neutrons and tritons, neither of which are quantitatively present with the excess heat. Scientists who are not in the field are discouraged because the expected fusion products are not present in quantities commensurate with the observed energy production, and scientists working in the field have not come up with an explanation in three and a half years as to why deuterons should fuse that is acceptable to the scientific community.

There have been proposals to change the name of the field: “solid state nuclear physics” has been suggested; “nuclear effects in metals” has also been put forth. I would strongly endorse a name change.

A reviewer of this manuscript has pointed out that even these names presuppose a nuclear component to the effect, which in the reviewer's eyes remains to be demonstrated, and has recommended “hydrogen energy” or “hydrogen in metals”, with the understanding that “hydrogen” is to include the isotopes.

"Status Report on Coherent Fusion Theory," Proceedings of The First Annual Conference on Cold Fusion, March 28-31, 1990, University of Utah Research Park, Salt Lake City, Utah. Abstract: "We are investigating two-step coherent reactions which begin through weak interaction mediated electron capture, which in hydrogen isotopes, would produce off shell (virtual) neutrons. No coulomb repulsion occurs for virtual neutrons. Virtual neutron capture by deuterons would yield tritium, and virtual neutron capture by protons by a factor of 5000 on a per nucleon basis, and corresponds to a heat-producing reaction."

"Over the years, Associate Hagelstein has come up with 150 versions of a theory trying to explain how cold fusion could create a nuclear reaction at room temperature without high levels of fusion byproducts."